Lubrication systems are used in internal combustion engines to lubricate and reduce friction within moving components in the engine, thereby increasing the operational life of the components and the engine. For example, pistons, crankshafts, bearings, etc., may be lubricated with oil by a lubrication circuit provided in an engine. The lubrication circuit may include a filter configured to reduce particulates from lubricant that may otherwise interfere with component lubrication. As the filter ages, particulates accumulate therein, eventually reaching a prevalence at which replacement of the filter is recommended.
U.S. Pat. No. 6,553,290 discloses methods of identifying clogging in a lubricant or fluid filter. Specifically, clogging in an engine oil filter is detected by measuring the pressure drop across the filter.
The inventors herein have recognized an issue with the approach identified above. Typical oil circuits provide one or more bypass or pressure relief valves that enable oil to bypass an oil filter at or above a threshold oil pressure. During conditions in which one or more of these valves are open, at least a portion of oil flowing through an oil circuit bypasses the filter. As such, pressure drops across the filter measured during these conditions are not fully indicative of filter clogging. Use of filter pressure drops during these conditions may lead to inaccurate identification of filter clogging, which may prompt unnecessary replacement of the filter.
One approach that at least partially addresses the above issues includes a method for a lubricant filter comprising indicating a condition of the filter based on a difference between a measured pressure differential and an expected pressure differential during select conditions in which all lubricant pumped by a pump upstream of the filter flows into the filter.
In a more specific example, the condition is one of a nominal condition and a degraded condition
In another example, the expected pressure differential is determined as a product of a lubricant flow rate and a lubricant viscosity.
In yet another example, the lubricant filter is configured to filter lubricant in a lubrication circuit including the pump, a filter bypass valve, and a pressure relief valve, and during the select conditions an outlet pressure of the pump is limited to less than one or both of respective setpoints of the filter bypass valve and the pressure relief valve.
In this way, pressure differentials across a lubricant filter may be accurately correlated to nominal or degraded filter conditions, which may reduce excessively early filter replacement, in turn reducing costs and hazardous waste issues associated with filter replacement. Thus, the technical result is achieved by these actions.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure. Finally, the above explanation does not admit any of the information or problems were well known.